Vibration motors (or “vibration actuators”) are built into mobile electronic devices, and are broadly used as devices to communicate to the user, through a vibration, that there is an incoming call, or that a signal, such as an alarm, has been generated, and have become indispensable devices in wearable devices, which are carried on the body of the user. Moreover, in recent years vibration motors have been of interest as devices by which to achieve haptics (skin-sensed feedback) in the human interfaces such as touch panels.
Among the various types of vibration motors under development, linear vibration motors that are able to generate relatively large vibrations through linearly reciprocating vibrations are of particular interest. This linear vibration motor provided with a straight stationary shaft, and a movable element is vibrated therealong, making it possible to achieve stabilized vibration, and making it possible to achieve resistance to damage, such as when there is a drop impact, through the movable element being held by the stationary shaft.
In the prior art for linear vibration motors equipped with stationary shafts, there have been proposals for one wherein a weight and a magnet are disposed on a movable element side, wherein an electric current is applied to a coil that is provided on the stator side to apply a driving force (a Lorentz force) to a magnet, wherein a through hole is formed through the movable element in the vibration direction and a single stationary shaft passes through the through hole (referencing Japanese Unexamined Patent Application Publication 2012-16153, below), and one wherein two stationary shafts are provided along the vibration direction, and a coil and a magnet are provided between the stationary shafts, where the movable element is supported slidably by the two stationary shafts (referencing Japanese Unexamined Patent Application Publication 2011-97747, below), and the like.